The present disclosure relates to vehicle controllers that operate the vehicle according to historical vehicle performance data.
Energy Economy Rating (EER) is an energy-based metric used in fuel economy testing to quantify fuel economy variability due to drive quality. The EER gives a quantitative measure of drive quality that includes the effects of both the energy expended and the distance driven on the fuel economy results. Some standardized fuel economy tests, such as those defined by the Environmental Protection Agency (EPA), require that the EER of the test vehicle be within specified limits. If the EER value violates these limits, the fuel economy results are deemed invalid. Numerical vehicle models simulate various vehicle physics including vehicle dynamics and fuel usage. These models can predict the fuel economy of the vehicles. A numerical cycle driver is the part of the numerical vehicle model that simulates human inputs including: braking, accelerating, shifting gears, engaging the clutch, and steering. In simulations used to predict fuel economy, the numerical cycle driver's goal is to calculate values of acceleration, braking, and possibly gear shifting events to get the velocity of the numerical vehicle model to match a target velocity trace (as defined by a drive cycle). For fuel economy predictions to reflect those obtained by human drivers, the values of acceleration, braking, and/or shifting calculated by the numerical cycle driver should be representative of human drivers. The numerical cycle driver applies some type of control strategy to cause the numerical vehicle model's velocity to match the target velocity (drive cycle). One type of control strategy is feedback control, such as Proportional Integrated Differential (PID) control. Numerical cycle drivers based solely on feedback control rely on the instantaneous difference between a target velocity and a simulated vehicle velocity from the model to calculate acceleration, braking, and shifting events. Such driver models do not have the ability to “look ahead”; therefore, numerical cycle drivers based solely on feedback control do not accurately represent a human driver's ability to anticipate future changes in vehicle velocity. As a result, the cycle driver overcompensates, applying too much acceleration and too much braking in order to achieve the target velocity. This overcompensation can affect the EER and/or cause the simulated fuel economy results to poorly reflect those achieved by human drivers.
It is desirable to allow the numerical cycle driver to anticipate and incorporate future values of target velocity. In some cases it is also desirable to tune the numerical cycle driver to be able to achieve a specified EER value while simultaneously achieving fuel economy ratings similar to those obtainable by human drivers. Therefore, it would be beneficial to take a desired EER value as an input when designing numerical cycle driver controllers used to simulate fuel economy tests.